Nuclear plant throws breaker, shuts down Unit 2, no danger to public or workers

Emergency conditions at nuclear power facilities are classified into one of four classifications. In order of least serious to most serious are:

Unusual event

Alert

Site area emergency

General emergency

Source: South Texas Project

BAY CITY - A failed breaker that caused an automatic shut down at South Texas Project's Unit 2 last week was no mock drill.

The unit went offline Wednesday in response to a non-safety equipment failure, said Buddy Eller, director of communication for South Texas Project.

There was no hazard to the public or to the employees at the plant, he added.

"We have an experienced and well-trained team at our facility, and our focus and priority is always on safety," said Ed Halpin, South Texas Project president and chief executive officer.

"Unit 2 operated as designed when the incident occurred. We have a root cause team working to determine the cause of the issue, and will work to safely and efficiently correct the condition and return the unit to service," he added.

Unit 2 remains offline but repairs have been completed and the company is beginning the process of restoring the unit to full power.

"Bringing the unit back will take a few days," said Eller. "We will conduct walk downs of the units and ensure that everything is working as designed."

The Forced Outage Team has worked around the clock to identify the issue associated with the trip and has safely and efficiently worked through a root cause, he added.

A walk down is standard operation procedures to make sure that everything is operating as designed, he said.

The trip occurred due to a switchgear equipment malfunction within the unit.

A switchgear essentially controls electrical connections to equipment within the unit, he said.

The unusual event classification indicated there was a minor problem at the plant that caused the company to enter into the emergency plan, he said.

The nuclear power plant officials have formed an event review team that is in the process of gathering the necessary facts to determine specifically what caused the trip, he said.

"Our initial investigation tells us there was an initial fault in the breaker, which caused an under voltage condition, which drove the unit trip," he said.

Outside experts, along with STP teams from across the site have gathered to fully understand what happened, he added.

"We do this so we can take the necessary actions to prevent this from happening again," he said.

The nuclear power plant performs emergency mock drills throughout the year with local, state and county officials.

Every two years, a graded exercise is performed by the Nuclear Regulatory Commission on the nuclear power plant.

"The goal of the exercise is to ensure that we have an integrated approach to communicating with the local community in the event we have an incident at the facility," he said.

Both units produce about 2,700 megawatts of energy - enough to supply about 2 million Texas homes.